Chlorine-containing propane or propene compounds having 1 or 2 fluorine atoms, such as a chlorine-containing monofluoro or difluoro propane compound represented by Formula (1): CFnCl3-nCHClCH2Cl, wherein n is 1 or 2, and chlorine-containing monofluoro or difluoro propene compounds represented by Formula (2): CFnCl3-nCCl═CH2, wherein n is 1 or 2, are useful as an intermediate for manufacturing various fluorocarbons and also as various kinds of functional materials. In particular, 2,3-dichloro-3,3-difluoropropene (HCFC-1232xf) represented by CF2ClCCl═CH2 is a promising candidate for use as a cleaning agent, dry-cleaning solvent, and resist-removing agent.
Among the compounds represented by Formula (1) or (2) described above, it is known that 1,1,2,3-tetrachloro-1-fluoropropane (HCFC-241db, bp. 157° C.) represented by CFCl2CHClCH2Cl, and 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc, bp. 113° C. to 114° C.) represented by CF2ClCHClCH2Cl can be prepared by fluorinating 1,1,1,2,3-tetrachloropropane (HCC-240db) (see Non-Patent Literature 1). However, because this method uses SbF3 and SbCl5 as the fluorinating agent, it poses a problem with regard to waste treatment upon disposal. Furthermore, in this method, the yield of HCFC-241db is only about 18%, and the yield of HCFC-242dc is only about 28%; therefore, a higher yield is desired.
As an alternative, a method is known wherein CF2ClCH═CH2 (HCFC-1242zf) or CF2ClCHClCH3 (HCFC-252dc) is used as a starting material and the starting material is chlorinated using chlorine. However, this method has drawbacks, including the fact that the starting material is not readily available, handling the chlorine is difficult, and the selectivity is low (see Patent Literature 1 and Non-Patent Literature 2).
An example of a known process for preparing 2,3,3-trichloro-3-fluoropropene (HCFC-1231xf, bp. 98.5° C. to 99° C.) represented by CFCl2CCl═CH2, and 2,3-dichloro-3,3-difluoropropene (HCFC-1232xf, bp. 57° C. to 58° C.) represented by CF2ClCCl═CH2 is that in which KOH is reacted with 1,1,2,3-tetrachloro-1-fluoropropane (HCFC-241db) or 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc) to remove hydrogen chloride (see Non-Patent Literature 1 and Non-Patent Literature 3, and Patent Literature 2). However, this method necessitates the problematic treatment of a large volume of waste and requires an improvement in the yield.
Patent Literature 3 discloses, as another related example, a process wherein 1,1,2,3-tetrachloropropene (HCC-1230xa, CCl2═CClCH2Cl) is fluorinated in a gas phase using a chromium-based catalyst. Patent Literature 4 also discloses a process for fluorinating 1,1,2,3-tetrachloropropene in a gas phase using a chromium-based catalyst. However, in these processes, fluorination advances too easily to result in a trifluorinated product, and it is extremely difficult to obtain a monofluorinated or difluorinated product.
Furthermore, Patent Literature 5 and Patent Literature 6 disclose that 1,1,2,3-tetrachloropropene (HCC-1230xa) represented by CCl2═CClCH2Cl, or 1,1,1,2,3-pentachloropropane (HCC-240db) represented by CCl3CHClCH2Cl can be fluorinated by using halogenated antimony or a like catalyst in a liquid phase. However, if fluorination is conducted through these processes, a trifluorocarbon compound is mainly obtained, and it is extremely difficult to obtain a monofluorinated or difluorinated product.
As disclosed in Patent Literature 3 to 6, in the method wherein a chlorine-containing propane compound or a chlorine-containing propene compound is directly fluorinated, the trifluorination advances too easily and it is extremely difficult to stop the reaction at the monofluorolination or difluorolination stage.